Degradation of the herbicide 2,4-D in river water—II. The role of suspended sediment, nutrients and water temperature

1980 ◽  
Vol 14 (12) ◽  
pp. 1689-1694 ◽  
Author(s):  
Harry J. Nesbitt ◽  
John R. Watson
Keyword(s):  
Water Temperature ◽  
River Water ◽  
Suspended Sediment ◽  
Sediment Nutrients

scholarly journals Assessing the performance of a suite of machine learning models for daily river water temperature prediction

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7065 ◽  
Author(s):  
Senlin Zhu ◽  
Emmanuel Karlo Nyarko ◽  
Marijana Hadzima-Nyarko ◽  
Salim Heddam ◽  
Shiqiang Wu
Keyword(s):  
Machine Learning ◽  
Water Temperature ◽  
River Water ◽  
Minor Role ◽  
Learning Models ◽  
Temperature Prediction ◽  
Flow Discharge ◽  
River Water Temperature ◽  
Machine Learning Models

In this study, different versions of feedforward neural network (FFNN), Gaussian process regression (GPR), and decision tree (DT) models were developed to estimate daily river water temperature using air temperature (Ta), flow discharge (Q), and the day of year (DOY) as predictors. The proposed models were assessed using observed data from eight river stations, and modelling results were compared with the air2stream model. Model performances were evaluated using four indicators in this study: the coefficient of correlation (R), the Willmott index of agreement (d), the root mean squared error (RMSE), and the mean absolute error (MAE). Results indicated that the three machine learning models had similar performance when only Ta was used as the predictor. When the day of year was included as model input, the performances of the three machine learning models dramatically improved. Including flow discharge instead of day of year, as an additional predictor, provided a lower gain in model accuracy, thereby showing the relatively minor role of flow discharge in river water temperature prediction. However, an increase in the relative importance of flow discharge was noticed for stations with high altitude catchments (Rhône, Dischmabach and Cedar) which are influenced by cold water releases from hydropower or snow melting, suggesting the dependence of the role of flow discharge on the hydrological characteristics of such rivers. The air2stream model outperformed the three machine learning models for most of the studied rivers except for the cases where including flow discharge as a predictor provided the highest benefits. The DT model outperformed the FFNN and GPR models in the calibration phase, however in the validation phase, its performance slightly decreased. In general, the FFNN model performed slightly better than GPR model. In summary, the overall modelling results showed that the three machine learning models performed well for river water temperature modelling.

scholarly journals Distribution of stable isotopes in water from an alpine river in China

2018 ◽  
Vol 13 (2) ◽  
pp. 371-381 ◽  
Author(s):  
Yuchuan Meng ◽  
Guodong Liu
Keyword(s):  
Isotopic Composition ◽  
Water Temperature ◽  
River Water ◽  
River Flow ◽  
Main Stream ◽  
The Tibetan Plateau ◽  
Stable Isotopic ◽  
Alpine River ◽  
Eastern Edge

Abstract The Hailuogou River, on the south-eastern edge of the Tibetan Plateau, receives a substantial portion of its flow from meltwater. The stable isotopic composition and water temperature were observed for waters collected from the main stream and selected tributaries. The results indicate that the river water is generally more depleted in 18O and 2H than groundwater, but more enriched than meltwater. The river water in the upper reaches is characterised by more negative isotopic values, the isotopic fingerprint of meltwaters, and lower temperatures. Both δ18O and δ2H increase significantly during passage from the upper basin downward, at least partly due to enrichment from tributary-inputs. There are also an altitude δ18O-effect of −0.1‰ per 100-m rise, and an altitude δ2H-effect of −0.8‰ per 100-m rise, along the main stream. The positive correlation between isotopic composition and water temperature further highlights the role of meltwater in regulating the river's isotope hydrology. The fraction of meltwater inputs over the total river flow ranges from 67% at Section 11 to 89% at Section 7, in the proglacial headwater region. The tributary-input enrichments and ice-snow melting are the main mechanisms controlling the isotopic composition of river runoff, but depending strongly on altitude.

Silicon Substitution for Calcium in the Shell of the Fingernail Clam, Musculium Transversum Studied By X-Ray Analysis

1980 ◽  
Vol 38 ◽  
pp. 560-561
Author(s):  
Judith A. Murphy ◽  
Anthony Paparo ◽  
Richard Sparks
Keyword(s):  
Carbonic Anhydrase ◽  
River Water ◽  
Food Chains ◽  
Well Water ◽  
Shell Formation ◽  
X Ray ◽  
Molluscan Shell ◽  
Fingernail Clams

Fingernail clams (Muscu1ium transversum) are dominant bottom-dwelling animals in some waters of the midwest U.S. These organisms are key links in food chains leading from nutrients in water and mud to fish and ducks which are utilized by man. In the mid-1950’s, fingernail clams disappeared from a 100-mile section of the Illinois R., a tributary of the Mississippi R. Some factor(s) in the river and/or sediment currently prevent clams from recolonizing areas where they were formerly abundant. Recently, clams developed shell deformities and died without reproducing. The greatest mortality and highest incidence of shell deformities appeared in test chambers containing the highest proportion of river water to well water. The molluscan shell consists of CaCO3, and the tissue concerned in its secretion is the mantle. The source of the carbonate is probably from metabolic CO2 and the maintenance of ionized Ca concentration in the mantle is controlled by carbonic anhydrase. The Ca is stored in extracellular concentric spherical granules(0.6-5.5μm) which represent a large amount of inertCa in the mantle. The purpose of this investigation was to examine the role of raw river water and well water on shell formation in the fingernail clam.

Measured and Modelled Chlorinated Contaminant Distributions in the St. Clair River Water

1986 ◽  
Vol 21 (3) ◽  
pp. 332-343 ◽  
Author(s):  
C.H. Chan ◽  
Y.L. Lau ◽  
B.G. Oliver
Keyword(s):  
River Water ◽  
Suspended Sediment ◽  
Water Samples ◽  
Concentration Distribution ◽  
Suspended Solids ◽  
Industrial Area ◽  
Concentration Profiles ◽  
Detroit River ◽  
Chemical Partitioning ◽  
Transverse Mixing

Abstract The concentration distribution of hexachlorobutadiene (HCBD), pentachloro-benzene (QCB), hexachlorobenzene (HCB) and octachlorostyrene (OCS) in water samples from transects across the upper and lower St. Clair River and the upper Detroit River were determined on four occasions in 1985. The data show a plume of these contaminants from the Sarnia industrial area. The fluxes and concentration profiles of the contaminants at Port Lambton have been modelled success fully using a simple transverse mixing model. A study on the chemical partitioning between the “dissolved” and “suspended sediment” phases shows that an important contaminant fraction is carried in the river by the suspended solids, particularly for lipophilie compounds such as HCB and OCS,

STUDY ON CHANGING IN RIVER WATER TEMPERATURE IN KYUSYU REGION

2018 ◽  
Vol 74 (5) ◽  
pp. I_79-I_84
Author(s):  
Yoji NODA ◽  
Tomoko MINAGAWA ◽  
Hidetaka ICHIYANAGI ◽  
Akihiko KOYAMA
Keyword(s):  
Water Temperature ◽  
River Water ◽  
River Water Temperature

Modelling lateral entrapment of suspended sediment in estuaries: The role of spatial lags in settling and M4 tidal flow

2014 ◽  
Vol 85 ◽  
pp. 126-142 ◽  
Author(s):  
Zhongyong Yang ◽  
Huib E. de Swart ◽  
Heqin Cheng ◽  
Chenjuan Jiang ◽  
Arnoldo Valle-Levinson
Keyword(s):  
Suspended Sediment ◽  
Tidal Flow

scholarly journals Exploring and Quantifying River Thermal Response to Heatwaves

Water ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 1098 ◽  
Author(s):  
Sebastiano Piccolroaz ◽  
Marco Toffolon ◽  
Christopher Robinson ◽  
Annunziato Siviglia
Keyword(s):  
Water Temperature ◽  
River Water ◽  
Thermal Response ◽  
Hydrological Regime ◽  
Management Policy ◽  
Extreme Weather Events ◽  
Thermal Dynamics ◽  
Depth Analysis ◽  
River Water Temperature

Most of the existing literature on river water temperature focuseds on river thermal sensitivity to long-term trends of climate variables, whereas how river water temperature responds to extreme weather events, such as heatwaves, still requires in-depth analysis. Research in this direction is particularly relevant in that heatwaves are expected to increase in intensity, frequency, and duration in the coming decades, with likely consequences on river thermal regimes and ecology. In this study we analyzed the long-term temperature and streamflow series of 19 Swiss rivers with different hydrological regime (regulated, low-land, and snow-fed), and characterized how concurrent changes in air temperature and streamflow concurred to affect their thermal dynamics. We focused on quantifying the thermal response to the three most significant heatwave events that occurred in Central Europe since 1950 (July–August 2003, July 2006, and July 2015). We found that the thermal response of the analyzed rivers contrasted strongly depending on the river hydrological regime, confirming the behavior observed under typical weather conditions. Low-land rivers were extremely sensitive to heatwaves. In sharp contrast, high-altitude snow-fed rivers and regulated rivers receiving cold water from higher altitude hydropower reservoirs or diversions showed a damped thermal response. The results presented in this study suggest that water resource managers should be aware of the multiple consequences of heatwave events on river water temperature and incorporate expected thermal responses in adaptive management policy. In this respect, additional efforts and dedicated studies are required to deepen our knowledge on how extreme heatwave events can affect river ecosystems.

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